This invention relates to a method of reducing the decomposition of liquid acetates by adding soluble amines thereto. In particular, it relates to a composition of an acetate and a very small amount of a soluble amine, which increases the storage life of the acetate.
Commercial quantities of various acetates are made by reacting the corresponding alcohol with acetic acid. For example, ethylene glycol monobutylether acetate (EBA) is made commercially according to the following reversible reaction: ##STR1## Fractional distillation is used to separate the product from the reactants and from the water that is formed. Once the product has been separated, it must be carefully handled and kept from all contact with water. Even the moisture in the air is enough to reverse the reaction and form acetic acid.
The acetates are used in various lacquers and the presence of acetic acid in the lacquer can cause corrosion and adherence problems, change surface properties, and adversely affect the stability of the lacquer product. Acetate users have set specifications for industrial acetates that require less than 200 ppm of acetic acid and less than 2000 ppm water. Although acetates meet the specifications when they are manufactured, by the time they are transported to the customer and are unloaded they often exceed the required specifications. Acetates that do not meet the specifications must be sold at steep discounts or returned to the manufacturer to undergo a costly purification process.
Many efforts have been made to solve this problem. It was suspected that the problem may be related to decomposition of the sulfonic acid type of catalyst used in manufacturing the acetate, such as p-toluene sulfonic acid. However, evidence supporting this mechanism has rarely been found in literature. Nonetheless, different distillation schemes have been tried to determine whether acetates purified are more stable. (See, for example, EP Application 521,488.) While the distillation schemes claimed in EP Application 521,488 appear to increase stability, the improved stability may be due to less moisture and it is impractical for acetate manufacturers to adapt the existing equipment to the new and more complicated scheme. It has also been proposed to add various hygroscopic or moisture-absorbing materials to the acetates, but as yet no such material has been found which is both effective and acceptable to the users of the acetates.